(* From: http://www.ocaml-tutorial.org/the_structure_of_ocaml_programs *)

let () =
  Random.self_init ();
  Graphics.open_graph " 640x480";

  let rec iterate r x_init i =
    if i = 1 then x_init
    else
      let x = iterate r x_init (i-1) in
      r *. x *. (1.0 -. x)
  in

  for x = 0 to 639 do
    let r = 4.0 *. (float_of_int x) /. 640.0 in
    for i = 0 to 39 do
      let x_init = Random.float 1.0 in
      let x_final = iterate r x_init 500 in
      let y = int_of_float (x_final *. 480.) in
      Graphics.plot x y
    done
  done;

  ignore (read_line ())